The International Space Station maintains an average altitud

The International Space Station maintains an average altitude of 400 km above the Earth\'s surface. a) Why does a person on the space station feel weightless? b) Calculate the acceleration of gravity at this elevation.

Solution

(a).Gravity exist even in space.International space station revolve around the earth.If gravity doesnot exist then the space station float away from the space.Space station is bound to the earth due to earth gravity.At the altitude of space station the gravity is 11% less than the gravity on the surface of the earth.i.e., weightless moment act on a person in space station.So a person on the space station feel weightless.

(b).Altitude h = 400 km

               = 400 x10 ³ m

radius of earth R = 6371 x10 ³ m

Mass of earth M = 5.972 × 10 ²⁴ kg

Accleration due to gravity at this elevation g \' = GM /(R+h) ²

Where G = Gravitational constant = 6.67x10 ^-11 Nm ²/kg ²

Substitute values you get , g \' = (6.67x10 ^-11)(5.972 x10 ²⁴ )/[(6371x10 ³ )+(400x10 ³)] ²

                                            = (3.983x10 ¹⁴ ) /(4.584x10 ¹³)

                                            = 8.687 m/s ²